The quality of rapeseed oil, as affected by potato chips frying at 180°C for 14 h, was investigated. The purpose of the study was to find out the quality deterioration of rapeseed oil with respect to time as affected by potato chips frying and to find the treatment that can be used for quality control. The parameters evaluated were refractive index, color, total polar material, free fatty acids, iodine value and peroxide value. There was a gradual increase in refractive index and color with time of frying which was found to be significant (P < 0.05) in the latter. Iodine value decreased significantly (P < 0.05) with time of frying. Peroxide value increased significantly (P < 0.05) with time of frying. After 14 h of frying, the total polar materials were 20.7 percent, indicating the need for replenishment or refinement of rapeseed oil. The refinement condition was realized when the excessive sodium silicate and activated bleaching earth added was 9 percent, the weigh ratio of excessive sodium silicate to activated bleaching earth was 1:4, the reaction temperature was 90°C, the reaction time was 35 min, and the rate of refining was 86.3 percent. It was found a new way to recover the frying oil.
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